Hi, normally for plaster ceiling, should it be the same color as walls ? Assuming that the color chosen is on the lighter shade like off white / milky white / misty white ( slightly greyish ) or just any other lighter shade color. I've seen many house design pictures where their walls and ceiling are the same color to achieve that seamless layout. But a painter told me that ceiling should not be the same color as walls, so this point I don't really get it, 10 out of 10 house designs their walls and ceiling are one color.

Would appreciate some advice before I start painting.

Yeah, i'm buying those 60ml small bottle paint tester, buying a few colors that I chosen, after that I'm planning to paint both walls and ceiling the same color tone.